Aircraft engine management for fuel conservation method

ABSTRACT

A method includes controlling an aircraft during descent, and controlling the engine pressure ratio of a jet engine so that the engine has a substantially equal pressure at the exhaust, and at the front of the engine during the descent.

RELATED APPLICATIONS

This application is a divisional of and claims benefit of U.S. patentapplication Ser. No. 12/832,491, filed on Jul. 8, 2010, titled “AIRCRAFTENGINE MANAGEMENT FOR FUEL CONSERVATION METHOD AND APPARATUS” (whichissued as U.S. Pat. No. 8,014,913 on Sep. 6, 2011), which is adivisional of and claims benefit of U.S. patent application Ser. No.11/831,697, filed on Jul. 31, 2007, titled “AIRCRAFT ENGINE MANAGEMENTFOR FUEL CONSERVATION” (which issued as U.S. Pat. No. 7,769,503 on Aug.3, 2010), which claimed the benefit of priority, under 35 U.S.C.§119(e), to U.S. Provisional patent application No. 60/820,972, filed onAug. 1, 2006, titled “AIRCRAFT ENGINE MANAGEMENT FOR FUEL CONSERVATION”,and U.S. Provisional patent application Ser. No. 60/824,941, filed onSep. 8, 2006, titled “AIRCRAFT ENGINE MANAGEMENT FOR FUEL CONSERVATION,”each of which is incorporated herein by reference in its entirety.

BACKGROUND

One of the larger costs in the airline industry is the cost of fuel.Currently companies in the airline industry run on very slim profitmargins. Management of any company, including the companies in theairline industry, knows that containing or reducing costs generally willyield higher profits. In addition to increasing company profits, if fuelcan be saved in the aircraft industry it is good for the earth and theenvironment. Fossil fuels are being used at increasing rates around theworld. World reserves of fossil fuels are limited. So, it isadvantageous to conserve as much fuel as possible so as to extend thelife of world reserves. This provides added time for development ofalternative means of energy.

Currently aircraft manufacturers and/or airlines set forth instructionsor protocols that include many aspects of the operations of an aircraftincluding preflight procedures, departure procedures, shut downprocedures, and procedures for securing the aircraft. The procedures arevery detailed and airline pilots and other professional pilots aregenerally taught to follow these procedures very closely. Proceduremanuals, such as an aircraft operating manual, and a cockpit operatingmanual, detail procedures for start, taxiing, take off, climb, cruise,descent, approach and landing. The current protocol for descent fromcruising altitude to about 11,000-9,000 feet generally instructs pilotsto set the engine at idle speed during the descent. One of theparameters that is measured and monitored for some airliner proceduresis the engine pressure ratio (EPR). The EPR is defined to be the totalpressure ratio across the engine. Thus, the EPR is the ratio of thepressure at the exhaust of a turbojet engine to the pressure measured atthe front face of the turbojet engine. A first pressure sensor is placedat the front face of a turbojet engine, and a second pressure sensor isplaced at the exhaust of the turbojet engine. Given these two pressures,the EPR can be easily determined for an operating engine and displayedto the pilot on a cockpit dial. The EPR is a parameter that is monitoredby a pilot during certain maneuvers. For example for one type ofaircraft, the EPR during takeoff is monitored so that it stays atapproximately 2.1. Of course, this EPR setting changes for differenttypes of aircraft, different engines, different environmental conditions(such as weather), and can also changes as a function of the weight ofthe aircraft. While cruising, the EPR varies as a function of altitude,temperature, weight and type of engine. In many aircraft the EPR ismonitored during many of the various procedures of the aircraft. Inother aircraft, the EPR is not monitored and the EPR is not a parameterthat is referred to during various procedures. However, the same factorsthat affect the EPR still affects the operations of the aircraft.

During descent from altitude, the protocol is to place the turbojet inan idle mode. During the idle mode, at about flight level 330 (33,000feet)+the EPR corresponding to idle mode is approximately 0.8. Thismeans that the pressure at the front of the turbojet is higher than thepressure at the exhaust of the turbojet. As a result, the engine acts asa speed brake during at least a portion of the descent. As the aircraftdescends the air gets more dense. The result is that the EPR rises asthe aircraft descends. In many instances the EPR may be near 1.0 at10,000 feet. Of course this can vary based on the atmospheric pressureat any given time. However, during the time when the EPR is less than1.0, the engine acts as a speed brake with as much as 0.3 to 63 squarefeet or more of frontage. With the engine acting as a speed brake, thedescent takes longer and wastes jet fuel. Most procedures require apilot to throttle back to idle during the descent. If an entire fleet ofairliners follow such a procedure for descent, the amount of fuel wasteis significant. Of course, when fuel costs are high, fuel expense isalso high.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is pointed out with particularity in the appended claims.However, a more complete understanding of the present invention may bederived by referring to the detailed description when considered inconnection with the figures, wherein like reference numbers refer tosimilar items throughout the figures, and:

FIG. 1 is a schematic diagram of a turbojet engine on an aircraft duringdescent, according to an example embodiment.

FIG. 2 is a schematic diagram of a turbojet and EPR control system,according to another example embodiment.

FIG. 3 is a process flow diagram for maintaining the EPR within aselected range during a descent, according to an example embodiment.

FIG. 4 is a block diagram of a computer system that executes programmingfor performing the above algorithm, according to an example embodiment.

FIG. 5 is a flow diagram of a method, according to an exampleembodiment.

FIG. 6 is a flow diagram of a method, according to an exampleembodiment.

The description set out herein illustrates the various embodiments ofthe invention, and such description is not intended to be construed aslimiting in any manner.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings that form a part hereof, and in which is shown by way ofillustration specific embodiments which may be practiced. Theseembodiments are described in sufficient detail to enable those skilledin the art to practice the invention, and it is to be understood thatother embodiments may be utilized and that structural, logical andelectrical changes may be made without departing from the scope of thepresent invention. The following description is, therefore, not to betaken in a limited sense, and the scope of the present invention isdefined by the appended claims.

FIG. 1 is a schematic diagram of an aircraft 100 that has a turbojetengine 200, according to an example embodiment. As shown in FIG. 1, theaircraft 100 is operating during a descent from a cruising altitude. Theturbojet engine 200 is attached to a wing 110 of the aircraft. It shouldbe noted that the turbojet engine 200 can be attached to variousportions of the wing or may be mounted in or near the verticalstabilizer (not shown) of the aircraft 100. The turbojet engine 200includes an intake 210 and an exhaust 220. The turbojet engine alsoincludes a turbine 230. The turbine includes several groupings ofturbine blades or buckets which compress air taken at the intake andheat the air. Along the length of the turbine 230 is a mechanism forintroducing and burning fuel. The combusted fuel turns several other orat least one other set of blades or buckets within the turbine 230 andleaves the turbojet engine 210 as exhaust 220. The exhaust 220 isdirected through a nozzle 222 at an end of the turbojet engine 200. Theturbojet engine 200 also includes several pressure sensors. In factthere are pressure sensors located at various points along the turbine.As shown in FIG. 1, the turbojet 200 includes a first sensor 202 at thefront face of the turbine 230 on the intake end 210 of the turbojetengine. A second sensor 204 is located at the end of the nozzle or atthe end of the turbojet 200.

FIG. 2 is a schematic diagram of the turbojet 200 along with an enginepressure ratio control system 250, according to an example embodiment.The turbojet engine 200 includes a housing 210 having an inlet end 212and a outlet end 214. The turbojet engine 200 also includes a compressoror turbine 230 for compressing the gases. The compressor or turbine 230is located between the inlet end 212 and the outlet end 214 of thehousing 210. The turbojet engine 200, as mentioned previously has asensor 202 at the front face of the turbine 230 and another pressuresensor 204 at the exhaust end of the turbojet engine and specifically atthe end of the nozzle 222. The EPR control system 250 includes an EPRdetermination module 252 and a speed control module 254. The speedcontrol, in the form of the speed control module 254, is communicativelycoupled to the compressor of turbine 230 for controlling the speed ofthe compressor.

The turbojet engine 200 and the controls also form a system. Theturbojet engine 200 includes a speed control 252 communicatively coupledto the compressor or turbine 230 for controlling the speed of thecompressor or turbine 230. The system also includes the first pressuresensor 202 positioned near the inlet end 212 of the turbojet engine 200,the second pressure sensor 204 positioned near the outlet end 214 of theturbojet engine 230. The system also includes a device, such as the EPRdetermination module 252, that determines the ratio of the output fromthe first pressure sensor 202 to the output of the second pressuresensor 204. The system also includes a controller, such as computersystem 2000 (shown in FIG. 4) that controls the speed control tomaintain the ratio between the output of the first pressure sensor 202and the output of the second pressure sensor 204 at a nearly constantvalue. In one embodiment, the controller 2000 controls the speed of thecompressor or turbine 230 to keep the ratio is in a range from 0.90 to1.15. In another embodiment, the controller 2000 controls the speed ofthe compressor or turbine 230 to keep the ratio substantially near 1.0.The controller 2000 is capable of controlling the ratio or keeping theratio substantially constant ratio during a descent of an airplane. Inone embodiment of the system, the second pressure sensor 204 ispositioned near the end of a nozzle portion of the housing 210 and thefirst pressure sensor 204 is positioned near a front face of thecompressor or turbine 230.

In operation the nozzle pressure is determined or measured at sensor 204and the front pressure is measured at sensor 202. The pressuremeasurements are input to the EPR determination module 252. The EPRdetermination module divides the pressure found at the nozzle by thepressure found at the front to determine the EPR. Output from the EPRdetermination module 252 is input to the speed control module 254. Speedcontrol module 254 can also be thought of as a pressure control module.The outputs from the pressure control module are input to variousportions of the engine or turbojet engine 230. The input from the EPRdetermination module 252 is compared to a desired EPR or selected EPR.If the measured and determined EPR is different from the selected ordesired EPR then the speed or pressure control module 254 output signalto the turbojet engine to change certain parameters so that the EPR willapproach or be substantially equal to the selected or desired EPR. Forexample, during descent of an aircraft 100 the desired EPR may beapproximately 1.0 or in some selected range about 1.0. For example, theselected range may be from 0.99 to 1.01 for the EPR. In anotherembodiment, the selected range might be from 0.95 to 1.05. And still inother embodiments the selected or desired range for the EPR may be from0.90 to 1.10. The speed control or pressure control 254 varies engineparameters to either bring the EPR within a desired range or bring theEPR close to a desired or selected value. For example, in one exampleembodiment, the speed or pressure control module 254 may vary the amountof fuel added to the compressed air which is to be combusted in theturbojet engine 200. In other examples, other parameters may be varied.

FIG. 3 is a process flow diagram of a method 300 for maintaining orcontrolling the EPR within a selected range or to a selected amountduring a descent of an aircraft, according to an example embodiment. Theaircraft is controlled during a descent from a cruising altitude asdepicted by reference numeral 310. In addition to controlling theaircraft the engine pressure ratio or EPR of the jet engine or turbojetis controlled so that the engine has a substantially equal pressure atthe exhaust as well as at the front of the engine as depicted byreference numeral 312. When the pressure at the front of the engine andthe pressure at the back of the engine are substantially equal itminimizes the effect of the engine acting as an air brake during thedescent of the aircraft.

Implementation of this method 300 or protocol has many advantages. Lessfuel is used since the turbojet or jet engine is not fighting thedescent. In other words, the engine is not acting as a speed brakeduring the descent. Descent is generally referred as the portion of theflight from cruising altitude to approximately 9,000-11,000 feet. Usingthe procedure where the jet engine or jet engines are set to idle duringthe descent, the EPR will move from a value of approximately 0.8 to 1.0during the descent. This is due to the fact that the air becomes moredense at lower altitudes. Implementation of the method 300 requires thatthe EPR remain at or near 1.0 during the descent. This requires thethrottle to be adjusted during the descent. The idle speed of theturbojet is generally lower than when the turbojet has an EPR ofapproximately 1.0. The time of descent will be slightly greater and takeslightly longer however the net amount of fuel burned will be lessduring the descent when using the method 300 when compared to theprocedure where the turbojet was placed in idle mode during descent.

FIG. 5 is a flow diagram of a method 500, according to an exampleembodiment. The method 500 includes measuring engine pressure near thefront of a turbojet engine 510, measuring the engine pressure near therear of a turbojet engine 512, and determining an engine pressure ratioby dividing the engine pressure near the rear of the turbojet engine bythe engine pressure near the front of the turbojet engine 514. Themethod 500 also includes controlling the engine speed 516, during adescent of an aircraft, so as to maintain the engine pressure ratio at asubstantially constant value during the descent. In one embodiment,controlling the engine speed 516 during a descent of an aircraft duringto maintain the engine pressure ratio at a substantially constant valueduring the descent includes maintaining the engine pressure ratio in arange of 1.11 to 0.87. In another embodiment, the engine pressure ratiois maintained within a range of 0.95 to 1.05. In still anotherembodiment, the engine pressure ratio is maintained within a range of0.98 to 1.02. In yet another embodiment, the engine pressure ratio ismaintained substantially near 1.0. Measuring the engine pressure nearthe front of a turbojet engine 510 includes measuring the pressure nearthe front face of a compressor of a turbojet engine, while measuringengine pressure near the rear of a turbojet engine 512 includesmeasuring the pressure near a nozzle shaped end of the turbojet engine.Controlling the engine speed 516 of the turbojet engine includescontrolling the rotational speed of a compressor of the turbojet engine.

FIG. 6 is a flow diagram of a method 600, according to an exampleembodiment. The method 600 includes placing an aircraft in an attitudefor descent 610, and maintaining the engine pressure ratio of a jetengine in the range of 0.90 to 1.15 during the descent 612. In oneembodiment, the engine pressure ratio is maintained in a range of 1.0 to1.05, and in another embodiment the engine pressure ratio is maintainedat a substantially constant value.

The system 200 for controlling the turbojet or other jet engine duringdescent can be controlled by a computer system 2000 to control eitherthe entire energy conversion process or specific portions of the energyconversion process. A block diagram of a computer system that executesprogramming for performing the above algorithm is shown in FIG. 4. Ageneral computing device in the form of a computer 2010, may include aprocessing unit 2002, memory 2004, removable storage 2012, andnon-removable storage 2014. Memory 2004 may include volatile memory 2006and non-volatile memory 2008. Computer 2010 may include, or have accessto a computing environment that includes, a variety of computer-readablemedia, such as volatile memory 2006 and non-volatile memory 2008,removable storage 2012 and non-removable storage 2014. Computer storageincludes random access memory (RAM), read only memory (ROM), erasableprogrammable read-only memory (EPROM) & electrically erasableprogrammable read-only memory (EEPROM), flash memory or other memorytechnologies, compact disc read-only memory (CD ROM), Digital VersatileDisks (DVD) or other optical disk storage, magnetic cassettes, magnetictape, magnetic disk storage or other magnetic storage devices, or anyother medium capable of storing computer-readable instructions. Computer2010 may include or have access to a computing environment that includesinput 2016, output 2018, and a communication connection 2020. One of theinputs could be a keyboard, a mouse, or other selection device. Thecommunication connection 2020 can also include a graphical userinterface, such as a display. The computer may operate in a networkedenvironment using a communication connection to connect to one or moreremote computers. The remote computer may include a personal computer(PC), server, router, network PC, a peer device or other common networknode, or the like. The communication connection may include a Local AreaNetwork (LAN), a Wide Area Network (WAN) or other networks.

Computer-readable instructions stored on a computer-readable medium areexecutable by the processing unit 2002 of the computer 2010. A harddrive, CD-ROM, and RAM are some examples of articles including acomputer-readable medium. For example, a computer program 2025 capableof providing a generic technique to perform access control check fordata access and/or for doing an operation on one of the servers in acomponent object model (COM) based system according to the teachings ofthe present invention may be included on a CD-ROM and loaded from theCD-ROM to a hard drive. The computer-readable instructions allowcomputer system 2000 to provide generic access controls in a COM basedcomputer network system having multiple users and servers.

A machine-readable medium that provides instructions that, when executedby a machine, cause the machine to perform various operations of theengine. A machine-readable medium includes a set of instructions. Theinstructions, when executed by a machine, cause the machine to performoperations that include measuring engine pressure near the front of aturbojet engine, measuring the engine pressure near the rear of aturbojet engine, determining an engine pressure ratio by dividing theengine pressure near the rear of the turbojet engine by the enginepressure near the front of the turbojet engine, and controlling theengine speed to maintain the engine pressure ratio at a substantiallyconstant value during a descent of an aircraft. The instructions of themachine-readable medium can cause the machine to maintain the enginepressure ratio at a substantially constant value in a range of 0.95 to1.05, or maintain the engine pressure ratio at a substantially constantvalue in a range of 0.98 to 1.02. In still another embodiment, the setof instructions cause the machine to maintain the engine pressure ratioat a substantially constant value substantially near 1.0.

It should be noted that the ratio of the engine pressures may not bereferred to in some turbojet engines as the engine pressure ratio. Theremay be equivalent measures or may be substantially equivalent measuresand a different term may be used.

The Abstract is provided to comply with 37 C.F.R. §1.72(b) to allow thereader to quickly ascertain the nature and gist of the technicaldisclosure. The Abstract is submitted with the understanding that itwill not be used to interpret or limit the scope or meaning of theclaims.

1. A computerized method for reducing a net amount of fuel consumedduring a flight when running a jet engine on an airplane, wherein thejet engine includes a housing having an inlet end and an outlet end, anda compressor located between the inlet end and the outlet end, andwherein the airplane includes an engine-control computer for controllingthe engine, the method comprising: measuring a first pressure near theinlet end of the jet engine; measuring a second pressure near the outletend of the jet engine; and controlling a speed of the compressor withthe engine-control computer to maintain a value of the second pressuredivided by the first pressure at a controlled first value in a range of0.9 to 1.15 at a plurality of descent altitudes from cruising altitudeto approximately 9,000-11,000 feet at which the jet engine, if set toidle, would have a value of the second pressure divided by the firstpressure of less than the first value in order to reduce the jet engineacting as a speed brake for the airplane during a descent of theairplane, in order to reduce the net amount of fuel consumed during theflight.
 2. The method of claim 1, wherein the controlling of thecompressor speed further includes maintaining the value of the secondpressure divided by the first pressure in a range of 0.90 to 1.10 duringthe descent of the airplane.
 3. The method of claim 1, wherein thecontrolling of the compressor speed further includes maintaining thevalue of the second pressure divided by the first pressure in a range of0.95 to 1.05 during the descent of the airplane.
 4. The method of claim1, wherein the controlling of the compressor speed further includesmaintaining the value of the second pressure divided by the firstpressure in a range of 0.98 to 1.02 during the descent of the airplane.5. The method of claim 1, wherein the controlling of the compressorspeed further includes maintaining the value of the second pressuredivided by the first pressure in a range of 0.99 to 1.01 during thedescent of the airplane.
 6. The method of claim 1, wherein thecontrolling of the compressor speed further includes maintaining thevalue of the second pressure divided by the first pressure substantiallyat 1.0 during the descent of the airplane.
 7. The method of claim 1,wherein the measuring of the second pressure further includes measuringthe second pressure near an end of a nozzle portion of the housing, andwherein the measuring of the first pressure further includes measuringthe first pressure near a front face of the compressor.
 8. Acomputerized method for reducing a net amount of fuel consumed during aflight when controlling engine speed of a jet engine of an aircraftduring a descent of the aircraft, wherein the aircraft includes anengine-control computer for controlling the engine, the methodcomprising: measuring engine pressure near a front of the jet engine;measuring the engine pressure near a rear of the jet engine; determiningan engine-pressure ratio (EPR) by dividing the engine pressure near therear of the jet engine by the engine pressure near the front of the jetengine; and controlling the engine speed with the engine-controlcomputer to maintain the engine-pressure ratio at a controlled first EPRvalue in a range of 0.9 to 1.1 at a plurality of descent altitudes fromcruising altitude to approximately 9,000-11,000 feet at which the jetengine, if set to idle, would have an engine-pressure ratio of less thanthe first EPR value in order to reduce the jet engine acting as a speedbrake for the aircraft during the descent of the aircraft, in order toreduce the net amount of fuel consumed during the flight.
 9. The methodof claim 8, wherein the controlling of the engine speed further includescontrolling the engine speed to maintain the engine-pressure ratio in arange of 0.95 to 1.05 during the descent of the aircraft.
 10. The methodof claim 8, wherein the controlling of the engine speed further includescontrolling the engine speed to maintain the engine-pressure ratio in arange of 0.98 to 1.02.
 11. The method of claim 8, wherein thecontrolling of the engine speed further includes controlling the enginespeed to maintain the engine-pressure ratio in a range of 0.99 to 1.01.12. The method of claim 8, wherein the controlling of the engine speedfurther includes controlling the engine speed to maintain theengine-pressure ratio substantially at 1.0.
 13. A computerized methodfor reducing a net amount of fuel consumed during a flight when runninga jet engine on an airplane, the jet engine including a speed-controlmodule, the method comprising: determining an engine pressure ratio(EPR) by dividing a first engine pressure near a rear of the jet engineby a second engine pressure near a front of the jet engine; andcontrolling an engine speed of the jet engine with the speed-controlmodule during a descent of the airplane to maintain the engine-pressureratio at a controlled first EPR value in a range between 0.9 and 1.15 ata plurality of descent altitudes from cruising altitude to approximately9,000-11,000 feet at which the jet engine, if set to idle, would have anengine-pressure ratio of less than the first EPR value in order toreduce the jet engine acting as a speed brake for the airplane duringthe descent of the airplane, in order to reduce the net amount of fuelconsumed during the flight.
 14. The method of claim 13, wherein thecontrolling of the engine speed further includes maintaining theengine-pressure ratio in a range between 0.9 and 1.10 during thedescent.
 15. The method of claim 13, wherein the controlling of theengine speed further includes maintaining the engine-pressure ratio in arange between 0.95 and 1.05 during the descent.
 16. The method of claim13, wherein the controlling of the engine speed further includesmaintaining the engine-pressure ratio in a range between 0.98 and 1.02during the descent.
 17. The method of claim 13, wherein the controllingof the engine speed further includes maintaining the engine-pressureratio in a range between 0.99 and 1.01 during the descent.
 18. Themethod of claim 13, wherein the controlling of the engine speed furtherincludes maintaining the engine-pressure ratio substantially at 1.0. 19.The method of claim 13, wherein the controlling of the engine speedfurther includes controlling a rotational speed of a compressor of thejet engine.
 20. The method of claim 13, wherein the controlling of theengine speed further includes maintaining the engine-pressure ratio in arange between 1.0 and 1.05 during the descent.